Threaded device for receiving an externally threaded screw

ABSTRACT

Threaded device (18) useful in a bracket (10) for mounting electrical components. The device (18) has a flat spring element (25) with two pressed tongues (20) with adjacent free ends. The tongues carry half nuts (45) with threaded half circular openings which are adjacent, so as to substantially define a threaded opening. A screw may be passed axially into the threaded opening so as to press the half nuts (45) apart against the bias of the tongues (20), without rotating the screw. On subsequent rotation of the screw, the half nuts (45) are drawn together by spring bias of the tongues (20) to enable the screw to threadedly engage the half nuts (45).

BACKGROUND OF THE INVENTION

This invention relates to a threaded device. More specifically, theinvention provides an improvement in threaded devices designed forengagement with a threaded screw upon insertion of the screw in theaxial direction thereof.

In one aspect, the invention provides a threaded device for receiving anexternally threaded screw, the device having an engaging portion whichis biased to a position at which it threadedly engages the screw whenreceived in the device, but movable against said bias under engagementby, and axial movement of, the screw with respect to the device, toenable the screw to pass the engaging portion without rotating thescrew.

SUMMARY OF THE INVENTION

Preferably, the engaging portion is resiliently biased to said position.

The engaging portion may comprise a leaf spring.

Preferably, there is more than one engaging portion. For example, theremay be two, three or four engaging portions arrayed about the locationof the axis of the screw when received by the device.

The free end of the or each engaging portion may be part threaded forthreadedly engaging the screw. Where there is more than one engagingportion, each may have a part threaded free end, the free ends beingconfigured so as, together, to substantially fully circumferentially andthreadedly engage the screw when threadedly received by the device.

The device may have a base portion having an opening through which thescrew may extend to be engaged by the or each engaging portion. Wherethe engaging portions are provided as leaf springs, the leaf springs maybe secured to a rear face of the base member, the screw in use beingpassed through the opening from a front face of the base member to beengaged by the engaging portions.

Where the engaging portions are in the form of leaf springs, these mayextend from locations at which they are fixed to the rear face, inwardlytowards the axis of the screw member when received, and rearwardly fromthe locations where they are fixed to the rear face, to free endportions which in use engage the screw. The or each engaging portion maybe movable in the rearward direction away from said rear face whenengaged by the screw for movement to the position at which axialmovement of the screw therepast is permitted without rotating the screw.The free ends may also be movable in the opposite direction, towards therear face, under screwing up action of the screw so that, for example,the or each portion is substantially flush with the rear face when thescrew is tightened.

The invention is particularly, but not exclusively adaptable for use inconnection with brackets for fixing of electrical fittings such as powerpoints and switches.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described by way of example only with referenceto the accompanying drawings in which:

FIG. 1 is a rear perspective view of a bracket for fixing of electricalequipment;

FIG. 2 is an enlarged fragmentary view of a rear part of the bracket,showing a threaded device formed in accordance with the invention;

FIG. 3 is a view like FIG. 2 but showing a front part of the bracket;

FIG. 4 is a plan view of a spring element incorporated into the threadeddevice of FIG. 2;

FIG. 5 is a lengthwise cross section of the spring element of FIG. 4;

FIGS. 6 to 9 are cross sectional views illustrating the operation of thethreaded device of FIG. 2;

FIG. 10 is a plan view of the bracket of FIG. 1 in use, prior to fixingof a switch thereto;

FIG. 11 is a view like FIG. 10, but showing a final fixed state of thebracket.

FIG. 12 is a view like FIG. 2, but showing a modified threaded deviceformed in accordance with the invention; and

FIGS. 13 and 14 are views like FIGS. 6 and 7 respectively butillustrating the operation of the modified threaded device of FIG. 12.

DETAILED DESCRIPTION OF THE DRAWINGS

The bracket 10 shown in FIG. 1 is formed of sheet metal having a majorportion 12 of generally planar form and a planar end portion 14, formedby bending from a metal blank. As shown in FIG. 11, the portion 14 has,stamped out and outwardly bent nail like portions 16 to permit thebracket to be fixed to, for example, a wall stud 100 so that the portion12 extends in parallel relation to, and immediately behind, an outerpanel 102 of the wall. The panel 102 is formed with an opening 104 whichis aligned with an opening 27 in portion 12 of the bracket 10. Inaccordance with usual practice, electrical fittings such as the switch110 shown in FIG. 11 can be fixed on the panel 102 by positioning itover the panel opening and screwing screws 140 through openings in thefitting, through drilled holes in the panel, and thence to engagethreaded recesses formed in portion 12. In the present instance, thesethreaded portions are defined by threaded devices 18 of like form asshown in FIG. 1. There is a separate device 18 positioned to eachrespective side of opening 27 in portion 12 of the bracket.

Referring to FIGS. 2 and 3, the device 18 shown comprises a springelement 25 which carries two half nuts 45.

The spring element 25 is shown in more detail in FIGS. 4 and 5. It isformed of flat spring steel which has been stamped and cut to form twotongues 20. In particular, the element 25 is of generally elongaterectangular form and is provided with two cuts 25a parallel to andspaced somewhat inwardly from the respective longer side edges of theelement 25. A central opening 25b is provided. From this opening 25a,respective cuts 25c are made to respective ones of the cuts 25a. Thetongues 20 are thus formed one to either side of the opening 25b, havingfree ends defined at the cuts 25c and side edges defined by the cuts25a. The tongues 20 are anchored to the remainder of the element 25 atends opposite the free ends. The tongues 20 are bent out of the plane ofthe remainder of the element 25 in the fashion shown most particularlyin FIG. 5. That is to say, the tongues extend at a small angle fromfixed ends at transverse fold lines 31 in a rearward direction towardsthe free ends thereof.

The half nuts 45 are secured such as by welding or riveting one to eachof the tongues 20. These each have half circular openings 47 at freeends thereof aligned with the end portions of the tongues which definethe opening 25b.

The element 25 has stamped out apertures 51 and is secured on the backof the portion 12 of bracket 10 by rivets 53 extending through these andthrough aligned openings (not shown) in the portion 12 of bracket 10.Portion 12 has an opening 29 which is aligned with the opening 25b andthe corresponding threaded opening defined by the two adjacent halfopenings 47.

FIGS. 7, 8 and 9 illustrate steps in securing the bracket to for examplea wall panel 70, by use of a screw 72 which passes through an opening 74in the panel thence through the aligned opening 29 in the bracket to bereceived by the device 18.

In the first step, the shank of the screw is pushed through the openings74 and 29 so that the end of the screw shank engages free end portionsof the half nuts 45 and pushes these laterally outwardly and rearwardlyas shown in FIG. 7. This action takes place against the resilient biasapplied to the half nuts 45 by virtue of the resilient tongues 20. Inthis way, it is possible to push the screw 72 fully home so that thehead thereof bears against the outer surface of the panel 70, withoutrotating the screw. Then, in the next step shown in FIG. 8, the screw 72is rotated so that the external thread on the shank of the screw engagespart threads of the threaded half openings 47 of the two half nuts 45.Under such rotation, the half nuts and resilient tongues 20 are drawninwardly towards the axis of the screw thread and forwardly towards thepanel 70. Under continued rotation, the position is finally reached atFIG. 9 where the half nuts are brought, against the resilient bias ofthe tongues 20, to a linearly aligned condition where the tongues 20 arelikewise brought forward to be coplanar with the remainder of theelement 25. At this point, further movement of the half nuts 45 in theforward direction is prevented by engagement of the tongues with therear of the portion 12 of the bracket 10, and continued rotation of thescrew 72 causes tightening of the screw to effect secure holding asbetween the panel 70 and bracket 10.

The described arrangement has been found particularly satisfactory inthat the inward and forward swinging action of the tongues 20 andattached half nuts 45 during screwing up brings about a particularlysecure threaded engagement and holding action. On the other hand, theoutward and rearward swinging of the half nuts which is permitted bysimply pressing the screw 72 inwardly as shown in FIG. 7 facilitatesquick positioning of the screw 72 for tightening up. In that regard, itis customary to provide brackets, switch gear or like electricalfittings with rather long screws 72 to accommodate the maximum thicknessof panels and electrical equipment to be secured which is likely to beencountered in everyday use. It is particularly tedious to have to fullyscrew up each screw into the receiving threaded openings of conventionalbrackets. On the other hand with the described construction, only a fewturns of the screw are required for tightening of the screw, regardlessof the thickness of panels and associated electrical equipment to beaffixed.

The described bracket 10 is, as mentioned, designed to be affixed to awall stud. Referring again to FIG. 10, it will be noted that the anglebetween the portions 12 and 14 of the bracket 10, shown as α in FIG. 10,is preferably made more than 90°, such as in the range 91° to 95°. Then,the bracket, when fixed to the stud 100, will extend with the portion 12projecting somewhat further in a forward direction (arrow "A") than theend thereof which joins the portion 14 and the bracket. Then, when thepanel 102 is subsequently installed over the front of the stud and thebracket, the free end of portion 12 is pushed rearwardly againstresilience of the bracket so as to ensure that the portion 12 lies flushagainst the panel 102 as shown in FIG. 11. This has the advantage thatwhen screws 140 are to be passed through the panel 102 to engage thethreaded devices 18, there is less prospect that the bracket will,through fixing irregularities or lack of squareness of the stud 100, bespaced away from the rear face of the panel 102, which may render itdifficult to locate the screw threaded devices 18. This improvement maybe applied even where conventional screw threaded openings are providedin the bracket 10 instead of the devices 18.

Thus, in a further aspect of the invention there is provided a bracketfor fixing electrical components to a panel, comprising first and secondportions extending at an angle to each other, the first portion beingarranged to lie flush against the rear face of said panel when thebracket is fixed in position by securing the second, then rearwardlyextending portion, of the bracket to a surface extending generallynormally to and rearwardly from the panel, wherein the bracket exhibitsresilience and the two portions are arranged to extend at an angle ofslightly more than 90° to each other. In particular, the said angle maybe in the range 91° to 95°.

The modified form of the threaded device 18 shown in FIGS. 12, 13 and 14is similar to that above described and, in these Figures, like referencenumerals devote like components to those described in FIGS. 1 to 11. Inthis case, however, the half nuts 45 each have small projections 45awhich extend outwardly from the ends thereof adjacent respective foldlines 31 of the spring element 25, and over those fold lines. As viewedfrom the side, the projections extend upwardly from the locations wherethey join the remainders of the half nuts to free ends of theprojection, so as to be inclined at a small angle to the planes of theremainders of the half nuts. This angle is such that in the "rest"position of FIG. 13, the projections 45a also extend away at a smallangle to the adjacent and underlying parts of the spring element 25.

The projections act to limited the extent of outward and "parting"movement of the half nuts when a screw is inserted as in FIG. 14. Thus,under action of the screw, the half nuts tilt only to the point where,as shown, the projections are rotated as to be brought into engagementwith the adjacent parts of the spring element 25.

The described construction has been advanced merely by way ofexplanation, and many modifications and variations may be made theretowithout departing from the spirit and scope of the invention as definedby the appended claims.

What is claimed is:
 1. A threaded device for receiving an externallythreaded screw, the device having a base portion and an engaging portionsecured thereto, said base portion having an opening through which ascrew may extend to be engaged by the engaging portion, said engagingportion being in the form of a leaf spring which extends from asubstantially fixed location to a free end and which is resilientlybiased to a position at which, at the free end, it threadedly engagesthe screw when received in the device by pressing the screw through saidopening, the engaging portion being movable against said bias underengagement by, and axial movement of, the screw with respect to thedevice, to enable the screw to pass the engaging portion withoutrotating the screw, the engaging portion having an abutment surfacepositioned thereon at a location spaced from said substantially fixedlocation in the direction away from said fixed end, and which isarranged to be brought into engagement with the base portion of thethreaded device to limit the movement of the engaging portion againstsaid base under engagement by, and axial movement of, the screw.
 2. Athreaded device according to claim 2, wherein there is more than oneengaging portion.
 3. A threaded device according to claim 2 whereinthere are two, three or four engaging portions arrayed about thelocation of the axis of the screw when received by the device.
 4. Athreaded device according to claim 3 wherein the free end of the or eachengaging portion is part threaded for threadedly engaging the screw. 5.A threaded device according to claim 4 wherein each said engagingportion has a part threaded free end, the free ends being configured soas, together, to substantially fully circumferentially and threadedlyengage the screw when threadedly received by the device.
 6. A threadeddevice as claimed in claim 1, the leaf springs being secured to a rearface of the base member, the screw in use being passed through theopening from a front face of the base member to be engaged by theengaging portions.
 7. A threaded device as claimed in claim 6, the leafsprings extending from locations at which they are fixed to the rearface, inwardly towards the axis of the screw member when received, andrearwardly from the locations where they are fixed to the rear face, tofree end portions which in use engage the screw.
 8. A threaded device asclaimed in claim 7 wherein the or each engaging portion is movable inthe rearward direction away from said rear face when engaged by thescrew for movement to the position at which axial movement of the screwtherepast is permitted without rotating the screw.
 9. A threaded deviceas claimed in claim 8 wherein the free ends are also movable in theopposite direction, towards the rear face, under screwing up action ofthe screw.